The first thing I usually do is to check the wiki for commonly known problems to see if any will effect me. Also, a quick Google search might help turn up any issues users are facing.
Upgrading an existing Fedora instance is very simple and can be done from the command line like a package update with DNF. Fedora Magazine has the simple instruction which is mostly a formatted snippet from the Wiki which has more details such as a FAQ and post upgrade suggestions.
The upgrade went smoothly and felt faster then going from 22 to 23 but I didn't time it. Once it finished and rebooted, I was able to log in and all the essential functions seemed to be working.
There were two things that didn't work as they did previously with Fedora 23. Conky, which I use to display a calendar on the desktop, was showing up in the wrong place. I have a dual monitor setup with my second monitor in a portrait orientation and I had the calendar on the second monitor. However, now it was showing the calendar near the middle of the first monitor instead as an windowed application. A quick search revealed that Conky has changed how its configuration format has changed but that wasn't the problem (Conky will try to convert it on the fly if it sees the old format). The windowed was because of a typo in my config that it ignored before (or maybe Conky changed what it expected).
I'm not sure what's causing the positioning problem though. It seems like what it thinks is the "top_right" is only on the primary monitor now so I had to assume the offset from the primary monitor (using negative value for the x,y coordinates).
The second problem was that I previously had different wallpapers for each monitor. Gnome (and specifically Cinnamon which is what I use) doesn't support this feature so I use Nitrogen to set the wallpapers, but in Fedora 24 Nitrogen crashes with "nitrogen --restore" or if run manually with just "nitrogen" it doesn't see the second monitor. After a lot of searching and going down various paths such as using dconf-editor to change the behavior of the file manager, I suspected that it might be because Fedora 24 is using Nitrogen 1.6 which has a log of changes especially in how it detects which type of desktop is being used. My solution for now was to install version 1.5.2 instead:
$ sudo dnf --showduplicates list nitrogen $ sudo dnf remove nitrogen $ sudo dnf install nitrogen-1.5.2-17.fc24The first dnf command will shows all the versions of Nitrogen available and the next two is to remove the current version and install the 1.5.2 version.